The metalcarbon bond in vinylidene, carbonyl, isocyanide and ethylene complexes

Density functional theory (DFT) calculations were carried out for trans-[RhX(L)(PMe3)2] (L=CCH2, CCHC6H5, CO, 2,6-Me2C6H3NC, C2H4) which served as model compounds for the analysis of the vibrational spectra of related complexes. The characterization of the metalcarbon stretching mode allowed to study the trans influence of a series of ligands on the metalcarbon bond in vinylidene, carbonyl and isocyanide complexes. Furthermore, the comparison of the FT-Raman spectra of the complexes trans-[RhF(CO)(PiPr3)2] and trans-[RhF(13C13CH2)(PiPr3)2] which possess the same reduced mass (13C13CH2 vs. CO) allowed for an evaluation of the RhC bond strength free of any mass effects and therefore only showing effects of electronic nature.